960 A/C Blower Cutting Off On Acceleration! Topic is solved

[email protected] · Post by **[email protected]** » 19 May 2005, 07:12

Help!

My 1995 960 A/C blower is cutting off when I accelerate...seems to also begin blowing hot air at that point...

Can anyone help me with a diagnosis and fix???

Thanks
Mike

boyoung960 · Post by **boyoung960** » 21 May 2005, 08:45

hi mike. it sounds like you have a vacuum leak at your air pump. easy fix, no worries!
bo

irbyjr · Post by **irbyjr** » 21 May 2005, 14:59

My 960 is doing the same. The dealer had replaced one vacuum motor earlier for this, but it is happening again. These pumps are expensive!
Thanks

[email protected] · Post by **[email protected]** » 23 May 2005, 09:45

Thanks...I was told that I need a new AC module and they need to tear open the dash???

Does this sound right?

Kmaniac in California USA · Post by **Kmaniac in California USA** » 23 May 2005, 19:01

I need a little clarification here before I can help you. When you say that the A/C blower cuts out on acceleration do you mean A) "the fan motor shuts off completely when you accelerate and turns back on again when you let up on the throttle" or B) "the air flow redirects from the dashboard vents to the defroster vents when accelerating, then returns to the dash vents when you let up on the throttle"? One can seem like the other, but I suggest you verify this for yourself before you pay someone to take apart your car.

The A/C vent controls are powered by engine manifold vacuum. The vacuum take off hose for the A/C controls is equipped with a check valve, which, when working properly, maintains steady vacuum on the vent control during heavy acceleration, like climbing a long hill. During periods of heavy acceleration, engine manifold vacuum drops to less the 10 inches of mercury, or zero under full throttle. If the vacuum check valve fails, you will notice the airflow from the dash vents stop when you accelerate. It is not that the fan motor stops, its that the loss of vacuum redirects the dampers, causing the air to flow through the defroster vents (the no vacuum default setting). Once you let up on the throttle, vacuum returns and the air flow redirects back through the dash vents.

The symtom you described sounds an awful lot like the scenerio I just described. I encounter the same condition in my 1986 740 GLE. Be sure to check your vacuum hoses for cracks or leaks, which can cause the same symtoms. You also have a vacuum reservoir tank under the car, in front of the front crossmember, which, if damaged and cracked, can cause the same symtoms as well. And this tank is the first thing to get damaged if you run over road debris.

For further informaiton, please read my post regarding "disfunctional A/C vent controls" dated October 1, 2004.

[email protected] · Post by **[email protected]** » 24 May 2005, 07:07

Thanks very much for the tip...I will check it again before I take it in for repair!

Mike

brianp · Post by **brianp** » 01 Jun 2005, 10:26

Sometime in the late 80 Ford motor company copies a great idea that they got from Mazda. Anytime the car was under hard accelleration accessoies like A/C that are detemental to the performance of the car would be shut down to preserve as much power as possible. My S90 does the same thing and entering freeways are much easier because of it.

Brian

amorqlubina · Post by **amorqlubina** » 11 Oct 2021, 09:14

As of today (11 October 2021), my 1992 Volvo 960 Sedan, no a/c coming vent on top, bottom completely. The a/c compressor and a/c blower working. Please tell me what to check and the location so I know what to replace. Thanks!